Creatures Caves

I actually have only ~~one~~ ~~two~~ ~~three~~ ~~two~~ ~~one~~ ~~two~~ one question right now (I keep posting them and figuring it out on my own eventually...), but undoubtedly there will be more, so I'll keep the title ambiguous to keep them all in this thread.

(This seemed like a wonderful idea at the time but considering the amount of edits I've done to add/remove questions to get no replies whatsoever I'm starting to question it D: Has the art of genetics been lost in the CC or is this thread just getting overlooked?)

Anyway the latest question has been driving me crazy for two weeks or so now...

In reworking the disease system for my genome I am trying to set it up so diseases go through phases depending on how high the level of antigen is (IE, when antigen 0 is at 10% it starts releasing histamine B, when it's at 50% it starts damaging the lungs, at 75% it starts to reduce oxygen levels, and so on), with each antigen having different effects.

As far as I can tell, the way to go about doing this would be to create a Chemical Reaction gene such as "1 antigen 0 = 1 antigen 0 + 1 Histamine B" followed up by a Chemical Receptor gene with the organ set to Current Reaction, The locus set to Reaction Rate, the chemical set to Antigen 0, the threshold set to 0.100, the nominal set to 0 and the gain set to 1. Theoretically, this should make the Histamine generating chemical reaction gene do nothing until Antigen 0 reaches 10% concentration at which point it should activate. Right?

Except that it doesn't. It doesn't seem to be activating at all until the antigen reaches 60% (and then the histamine levels go through the roof). It's like it's just picking its own threshold or something-- either that or the reaction itself is taking so long that it doesn't even register until the antigen level is much higher (the rate of the chemical reaction gene -is- set to instant).

So am I missing something about how C3 genetics works or is there some other strange gene I don't know about messing with my threshold level?

Any help would be very much appreciated ;_; This is really driving me crazy.
Thanks guys.